Analysis of information sources in references of the Wikipedia article "Mosque-Madrasa of Sultan Hasan" in English language version.
In any case, the dismantling of the pyramid began before 1250. For example, the historian Abd al-Latif tells us that the small pyramids were torn down during the time of the sultan Saladin (1175-1193). The stones were used for building dams, for instance. Around the middle of the fourteenth century, under Sultan Hassan, stone blocks from the Great Pyramid were used to build his famous mosque. Many others followed his example, but despite all the damage and natural erosion, the Great Pyramid endured.